1. Field of the Invention
The present invention relates to a pushing device for a tooth restoration material mixed and kneaded in a capsule, which are for pushing out a desired amount of the mixed and kneaded tooth restoration material toward a treating portion of a patient. A capsule for a tooth restoration material is mounted on the pushing device, and the tooth restoration material is made by mixing and kneading predetermined amounts of a powder component and a liquid component, which are isolatedly housed in the capsule so as to constitute the tooth restoration material such as dental cement or the like.
2. Description of the Conventional Art
As a dental treatment method widely used for filling the tooth restoration material such as dental cement or the like to a caries portion of a tooth, there is a treatment method comprising the steps of isolatedly housing predetermined amounts of a powder component and a liquid component constituting the tooth restoration material in one capsule for the tooth restoration material; destroying a partition wall for isolating the powder component and the liquid component in the capsule for a tooth restoration material immediately before using the tooth restoration material; mounting the capsule for a tooth restoration material on an automatic kneading device so as to mix and knead the powder component and the liquid component immediately after destroying the partition wall; setting the capsule for a tooth restoration material to a pushing device for the tooth restoration material; and pushing out a desired amount of the mixed and kneaded tooth restoration material from a nozzle of the capsule for a tooth restoration material toward a treating portion of a patient.
As for the capsule for a tooth restoration material used for such the treatment method, for example, there is a capsule for mixing and kneading a tooth restoration material therein, where the tooth restoration material consists of fixed amounts of two components, that is, a powder component and a liquid component measured in advance, and directly administering the mixture to a portion of a tooth of patient to be restored, comprising a cylinder-shaped capsule body having a mixing compartment for housing the powder component and provided with a first opening forming part on a center axis at an end thereof for forming a mixture outlet hole; a liquid cup having a liquid component housing room therein for housing the liquid component and provided with a second opening forming part on a center axis at an end thereof for forming an outlet hole for the liquid component, where the liquid cup is fitted over the cylinder-shaped portion for forming the mixing compartment of the capsule body and provided with a projection stopper on an outer surface thereof near a rear end thereof; a plunger having a rod-shaped projection for tearing the second opening forming part of the liquid cup and the first opening forming part of the capsule body and being fitted over the cylinder-shaped portion in the liquid cup; and a nozzle having an rear end, which has a shape corresponding to the front end of the capsule body and being connected to the front end of the capsule body. The projection stopper has such a size as prevent to easily take the liquid cup into the capsule body when tearing the second opening forming part so as to form the outlet hole for the liquid component, but does not prevent to take the liquid cup into the capsule body when applying large force. (for example, refer to Japanese Patent Application Laid Open No. 2002-191622.)
In order to push out the tooth restoration material toward a treating portion of a patient using such the capsule for a tooth restoration material, there is a method comprising the steps of pressing the plunger so as to tear the second opening forming part in the liquid cup and to flow the liquid component in the liquid cup into the mixing compartment of the capsule body; mixing and kneading the powder component housed in the mixing compartment in advance and the liquid component flowing-in from the liquid housing room using a kneading device for the capsule for a tooth restoration material; setting the capsule on the pushing device of the tooth restoration material; pressing the plunger so as to tear the first opening forming part of the capsule body; and pushing out a desired amount of the mixed and kneaded tooth restoration material from the nozzle of the capsule for a tooth restoration material toward a treating portion of a patient.
As the kneading device for the capsule for a tooth restoration material, which is used for mixing and kneading the powder component and the liquid component in the mixing compartment of the capsule for a tooth restoration material, for example, there is a device for mixing and kneading these components by shaking or rotating a capsule holding part for holding the capsule for a tooth restoration material.
Further, as the pushing device for the tooth restoration material, there is a device for pushing out a desired amount of the mixed and kneaded tooth restoration material from the nozzle of the capsule for a tooth restoration material toward a treating portion of a patient by using the capsule for a tooth restoration material, where the powder component and the liquid component are mixed and kneaded in the mixing compartment, comprising:
a housing body in which a mounting part of the capsule for a tooth restoration material, a guiding path, a supporting part and a reset pusher guiding path are provided at an upper part of the housing body, where the mounting part is provided at a front end, the guiding path is movably inserted with a piston rod and provided through at a front part, the supporting part supports a push plate, works as a guiding path of the piston rod and is suspended at a center part, and the reset pusher guiding path is inserted with a reset pusher mounted on a rear end of the piston rod and provided through at a rear part, a screw for adjusting a position of a stopper plate is screwed to a female screw provided just beneath the reset pusher guiding path, and a spot faced part for specifying an initial position of a lever is provided at a lower part of the front part;
a reset pusher which is inserted into the reset pusher guiding path of the housing body, has a cylindrical shape with a closed rear end and has a flange on an outer periphery of a front part thereof;
a piston rod penetrating in the guiding path of the housing body and the guiding path of the supporting part, being inserted in the reset pusher at the rear end thereof, having a fixed pitch groove at a part which is engaged with at least the push plate in the housing body, having a groove for fitting a snap ring provided at a part positioned at a rear end of the guiding path in the housing body in an initial state, having a stepped part provided at the frontward side from the groove for fitting, and having such a diameter as engages to a rear end of the capsule for a tooth restoration material at a part at frontward side from the stepped part;
a stopper plate having an upper end and a lower end constantly pressed by a spring for the stopper plate, so that the upper end contacts to an upper part of the front end of the reset pusher, and the lower end contacts to the front end of the screw for adjusting a position of the stopper plate, and having an engaging hole, where an upper end and lower end of the engaging hole are engaged with an outer periphery of the piston rod penetrating the engaging hole so as to prevent to move the piston rod in the axial direction by friction force when the stopper plate is inclined, and the upper end and the lower end of the engaging hole are not engaged with the outer periphery of the piston rod so as not to prevent to move the piston rod in the axial direction when the stopper plate becomes perpendicular to the axial center of the piston rod by frontwardly pushing of the reset pusher;
a push plate in which, when a lever is not operated, the push plate is constantly pressed by the spring for a push plate so that an rear face of an upper part contacts with a front face of the supporting part in the housing body, the push plate becomes perpendicular to the axial center of the piston rod and the engaging hole penetrated with the piston rod is not engaged with the outer periphery of the piston rod, and when the lever is operated and a top end thereof contacts with the front face of the supporting part inclined so as to be, the upper end and the lower end of the engaging hole are engaged with the outer periphery of the piston rod so as to enable to frontwardly move the piston rod by frictional force in the axial direction;
a spring for pushing back a piston rod being provided between rear face of a fixing nut and front face of a ring and giving a force for not pushing back the piston rod in the axial direction to overcome the frictional force occurred when the engaging hole of the stopper plate is engaged with the outer periphery of the piston rod, where the fixing nut is screwed at the backward side from the mounting part of the front end of the housing body, a through hole is provided in an inner surface of the fixing nut, the front part of the piston rod can be slid and moved in the axial direction in the through hole, and rear face of the ring is supported by the snap ring loosely fitted to the piston rod and engaged with the groove for fitting a snap ring of the piston rod; and
a lever being rotatably mounted on a lever shaft fixed at the housing body, having a spring supporting part at a rear end of upper part thereof on which a front end of a tension spring is mounted, where a rear end of the tension spring is mounted on a spring supporting member at a rear part of the housing body, having a projection part at a front part thereof, where the projection part is contacted with the spot faced part of the housing body, and having a push plate pressing part at an upper part thereof, where the push plate pressing part is contacted with a lower end rear part of the push plate. (for example, refer to Japanese Patent Application Laid Open No. 1997-253085)
According to the above-described pushing device for a tooth restoration material mixed and kneaded in the capsule, a desired amount of the tooth restoration material can be pushed out without large force for pushing out the material from the inside of the capsule for a tooth restoration material. However, when the tooth restoration material mixed and kneaded in the capsule for a tooth restoration material is pushed out from the inside of the capsule using the pushing device for a tooth restoration material, a residual powder component or the like being not mixed and kneaded in the capsule body of the capsule for a tooth restoration material is jetted outwardly from the space between the inner periphery of the capsule body and the outer periphery of the liquid cup at the rear end part of the capsule for a tooth restoration material (especially, a powder component, which enters into a slight space existing between an inner periphery of the capsule body and an outer periphery of the liquid cup by increasing of pressure in the mixing compartment, when the plunger is pressed so as to tear the second opening forming part of the liquid cup by a rod-like projection at a top end part thereof and to flow the liquid component in the liquid cup into the mixing compartment of the capsule body). So, there are problems that the jetted powder component are poured on a face of a patient or a dentist, and a patient or a dentist inhales the powder component by mistake. Further, since the powder component enters into the housing body, there is a problem that the pushing device itself for the restoration material mixed and kneaded in the capsule causes the malfunction.
Further, the pushing device for a tooth restoration material mixed and kneaded in a capsule has the structure that, when the lever is operated so as to incline the push plate, the upper end and the lower end of the engaging hole of the push plate are engaged with the outer periphery of the piston rod in which the groove having a fixed pitch is formed at least at the part engaged with the push plate, and the piston rod is moved forward in the axial direction by the frictional force thereof. Thus, when the engaging hole of the push plate is a round hole, the engaging hole and the outer periphery of the piston rod are engaged by point contact, and when the engaging hole of the push plate is an elliptical hole, the engaging hole and the outer periphery of the piston rod are engaged by line contact with short engaging length, so that the contacting area of the engaging hole and the outer periphery of the piston rod are remarkably small. So, the force generated by operating the lever concentrates on the remarkably slight contacting area, and when the operation for moving the piston rod forward in the axial direction are repeated, the engaging hole of the push plate and the outer periphery of the piston rod are easily abraded, deformed or damaged in a short period of time, so that there is a problem that life of the push plate or the piston rod is short. Further, as described above, the residual powder component or the like being not mixed and kneaded in the capsule body of the capsule for a tooth restoration material is jetted outwardly from the rear end part of the capsule for a tooth restoration material. So, if the powder component or the like enters into the housing body so as to adhere at the outer periphery of the piston rod or the engaging hole of the push plate, the engaging hole of the push plate and the outer periphery of the piston rod are not engaged and are slid by the adhered powder component or the like at the time of operating the lever. Thus, there are problems that the piston rod cannot be moved forward in the axial direction, and an operator may be injured unexpectedly since the lever is rotated rapidly.